JP2009224384A - Polishing pad, and manufacturing method of semiconductor device - Google Patents

Abstract

An object of the present invention is to provide a polishing pad capable of detecting an optical end point with high accuracy in a state where polishing is performed and preventing slurry leakage even when used for a long time.
A polishing pad (1) in which a polishing layer (10) is laminated on a cushion layer (13) via an intermediate layer (12), wherein the polishing layer (10) includes a polishing region (8) in which a first opening (11) is formed, and a first opening (11). The light transmission region 9 is provided in the portion 11 and is in contact with the intermediate layer 12. The intermediate layer 12 and the cushion layer 13 are smaller than the light transmission region 9 and overlap the light transmission region 9. A polishing pad comprising the second opening 14 formed as described above, wherein the intermediate layer 12 is a composite film obtained by depositing ceramic on a resin film.
[Selection] Figure 2

Description

  The present invention relates to a polishing pad used for planarizing unevenness on a surface of an object to be polished such as a semiconductor wafer by chemical mechanical polishing (hereinafter also referred to as CMP). Specifically, the polishing state and the like are detected by optical means. The present invention relates to a polishing pad having a window (light transmission region) for performing the same and a method of manufacturing a semiconductor device using the polishing pad.

  When manufacturing a semiconductor device, a conductive film is formed on the surface of a semiconductor wafer (hereinafter also referred to as a wafer), and a wiring layer is formed by photolithography, etching, or the like. A process for forming an interlayer insulating film is performed on the surface of the wafer, and these processes cause irregularities made of a conductor such as metal or an insulator on the wafer surface. In recent years, miniaturization of wiring and multilayer wiring have been advanced for the purpose of increasing the density of semiconductor integrated circuits, and along with this, technology for flattening the irregularities on the wafer surface has become important.

  As a method for flattening the irregularities on the wafer surface, a CMP method is generally employed. CMP is a technique of polishing using a slurry-like abrasive (hereinafter also referred to as slurry) in which abrasive grains are dispersed in a state in which a surface to be polished of a wafer is pressed against a polishing surface of a polishing pad.

  As shown in FIG. 1, for example, a polishing apparatus generally used in CMP includes a polishing platen (platen) 2 that supports a polishing pad 1 and a support table (polishing) that supports an object to be polished (wafer or the like) 4. A head) and a backing material for uniformly pressing the wafer and a supply mechanism of the abrasive 3. The polishing pad 1 is attached to the platen 2 by attaching it with a double-sided tape, for example. The platen 2 and the support base 5 are disposed so that the polishing pad 1 and the object to be polished 4 supported by each of the platen 2 and the support base 5 face each other, and are provided with rotating shafts 6 and 7 respectively. Further, a pressing mechanism for pressing the object to be polished 4 against the polishing pad 1 is provided on the support base 5 side.

  In performing such CMP, there is a problem in determining the wafer surface flatness. In other words, it is necessary to detect when the desired surface characteristics or planar state is reached. Conventionally, with regard to the thickness of the oxide film, the polishing rate, and the like, a test wafer is periodically processed, and after confirming the result, a product wafer is polished.

  However, in this method, the time and cost for processing the test wafer are wasted, and the polishing result differs between the test wafer and the product wafer that have not been processed in advance due to the loading effect peculiar to CMP. Unless it is actually processed, it is difficult to accurately predict the processing result.

  Therefore, recently, in order to solve the above-mentioned problems, a method capable of detecting when a desired surface characteristic or thickness is obtained on the spot during the CMP process is desired. Various methods are used for such detection, but optical detection means are becoming mainstream in terms of measurement accuracy and spatial resolution in non-contact measurement.

  Specifically, the optical detection means is a method of detecting an end point of polishing by irradiating a wafer with a light beam through a window (light transmission region) through a polishing pad and monitoring an interference signal generated by the reflection. It is.

  In such a method, the end point is determined by monitoring the change in the thickness of the surface layer of the wafer and knowing the approximate depth of the surface irregularities. When such a change in thickness becomes equal to the depth of the unevenness, the CMP process is terminated. Various types of polishing pads have been proposed in the past for use in the polishing end point detection method using such optical detection means. However, in the polishing pad used in the conventionally proposed polishing end point detection method, moisture in the slurry permeates the cushion layer constituting the polishing pad due to slurry leakage, and the back surface of the window member constituting the light transmission region ( Water droplets or cloudiness occurs on the non-polished surface. As a result, when the end point is detected, the light does not pass through the window member, which may cause a problem. Further, the moisture in the slurry permeates and the cushion layer swells and deforms. As a result, the polishing characteristics of the polishing pad may deteriorate over time.

  In the following Patent Documents 1-4, in order to prevent moisture in the slurry from penetrating into the cushion layer due to slurry leakage and causing water droplets and fogging on the back surface of the window member, or to prevent swelling deformation of the cushion layer. In addition, a polishing pad is described in which an intermediate layer made of polyethylene terephthalate or a waterproof material is disposed between the polishing layer and the cushion layer. Further, in Patent Document 5 below, the window member and the polishing layer are integrally molded in order to prevent moisture in the slurry from penetrating into the cushion layer due to slurry leakage from the gap between the window member and the polishing layer. A polishing pad is described. However, even with these polishing pads, water in the slurry permeates into the cushion layer, so that water droplets and cloudiness may occur on the back surface of the window member, and further, the cushion layer swells and deforms, and the polishing characteristics over time. May get worse.

Further, in Patent Document 6 below, in order to prevent moisture in the slurry from penetrating into the cushion layer of the polishing pad due to slurry leakage and causing swelling deformation, an adhesive layer is provided on both sides of the flexible urethane foam sheet, and water vapor permeation is achieved. A double-sided PSA sheet with a reduced rate is described. However, in such a double-sided PSA sheet, moisture penetration could not be sufficiently prevented, the cushion layer swelled and deformed, and the polishing characteristics sometimes deteriorated over time.
Japanese Patent Laid-Open No. 11-156701 Japanese translation of PCT publication No. 2003-510826 Japanese Patent No. 3913969 Japanese Patent Laid-Open No. 10-83977 Patent No. 4019087 Japanese Patent Laid-Open No. 2004-253764

  An object of the present invention is to provide a polishing pad that can detect an optical end point with high accuracy in a state where polishing is performed, and can prevent slurry leakage even when used for a long period of time. Moreover, it aims at providing the manufacturing method of the semiconductor device using this polishing pad.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the polishing pad described below, and have completed the present invention.

  That is, the polishing pad according to the present invention is a polishing pad in which a polishing layer is laminated on a cushion layer via an intermediate layer, and the polishing layer includes a polishing region in which a first opening is formed, and the first A light transmissive region disposed in the opening and in contact with the intermediate layer, wherein the intermediate layer and the cushion layer are smaller than the light transmissive region and overlap the light transmissive region. It is provided with the formed 2nd opening part, The said intermediate | middle layer is a composite film which vapor-deposited the ceramic on the resin film, It is characterized by the above-mentioned.

  In CMP, a polishing pad and an object to be polished such as a wafer rotate and revolve together, and polishing is performed by friction under pressure. During polishing, various (especially horizontal) forces are applied to the light transmission region, the polishing region, and the cushion layer, so that a peeling state is always generated at the boundary of each member. It is considered that the conventional polishing pad is easily peeled off at the boundary of each member, and a gap is generated at the boundary to cause slurry leakage. It is considered that water droplets or cloudiness occurs on the back surface of the light transmission region due to this slurry leakage, so that light does not pass through the light transmission region when detecting the end point, and as a result, the end point detection accuracy is lowered or disabled.

  On the other hand, the polishing pad according to the present invention is a polishing pad in which a polishing layer is laminated on a cushion layer via an intermediate layer, and the intermediate layer is a composite film obtained by depositing ceramic on a resin film. Even when a gap is generated at the boundary between the light transmitting region and the slurry leaks, slurry leakage can be reliably prevented in the intermediate layer. As a result, water droplets and cloudiness do not occur on the back surface of the light transmission region, and it is possible to prevent a decrease in end point detection accuracy even when used for a long time. Furthermore, since moisture in the slurry can penetrate into the cushion layer and prevent the cushion layer from swelling and deforming, the polishing characteristics of the polishing pad are stabilized.

  In the above, it is preferable that the composite film has a tensile strength of 50 to 500 MPa and a thickness of 3 to 125 μm. When the composite film has a tensile strength of 50 to 500 MPa, the handleability during lamination is further improved. In consideration of handleability at the time of laminating, the tensile strength of the composite film is preferably 100 to 400 MPa, and more preferably 220 to 300 MPa. On the other hand, when the thickness of the composite film is 3 to 125 μm, the permeation of water vapor can be prevented, slurry leakage can be more effectively prevented, and the handling property at the time of laminating can be further improved. Considering the effect of preventing slurry leakage and the handleability during lamination, the thickness of the composite film is preferably 3 to 50 μm, more preferably 5 to 20 μm.

  Another polishing pad according to the present invention is a polishing pad in which a polishing layer is laminated on a cushion layer via an intermediate layer, wherein the intermediate layer is a composite film in which a ceramic is deposited on a resin film. To do. According to this configuration, since the intermediate layer is a composite film obtained by depositing ceramic on a resin film, slurry leakage can be reliably prevented in the intermediate layer. Thereby, since the swelling deformation of the cushion layer can be prevented, the polishing characteristics of the polishing pad are stabilized.

  Furthermore, the present invention relates to a semiconductor device manufacturing method including a step of polishing a surface of a semiconductor wafer using the polishing pad.

  FIG. 2 is a schematic cross-sectional view of a polishing pad according to the present invention. As shown in FIG. 2, the polishing pad 1 of the present invention has a polishing layer 10 laminated on a cushion layer 13 with an intermediate layer 12 interposed therebetween. The polishing layer 10 includes a polishing region 8 in which a first opening 11 is formed, and a light transmission region 9 disposed in the first opening 11 and in contact with the intermediate layer 12. The intermediate layer 12 and the cushion layer 13 include a second opening 14 that is smaller than the light transmission region 9 and formed so as to overlap the light transmission region 9. According to this configuration, there is a space 15 surrounded by the back surface of the light transmission region 9 and the cross section of the second opening 14. When such a space portion 15 exists on the back surface of the light transmission region 9, when a gap is generated at the boundary between the polishing region 8 and the light transmission region 9 and slurry leakage occurs, moisture in the slurry permeates the cushion layer 13, As a result, water droplets or cloudiness may occur on the back surface of the light transmission region 9.

However, in the polishing pad 1 according to the present invention, since the intermediate layer 12 is a composite film obtained by depositing ceramic on a resin film, slurry leakage can be reliably prevented in the intermediate layer 12. In order to more reliably prevent slurry leakage, the water vapor permeability of the composite film at a thickness of 25 μm is preferably less than 5 gm ² · day.

  In the present invention, the “composite film obtained by depositing ceramic on a resin film” constituting the intermediate layer 12 means a composite film obtained by depositing ceramic (silica / alumina) on at least one surface of the resin film. The thickness of the ceramic vapor-deposited film formed on the resin film is not particularly limited as long as the composite film exhibits an effect of preventing slurry leakage, and examples thereof include 0.01 to 10 μm. Commercially available products can be suitably used as the composite film. For example, “Ecosia VE500 (manufactured by Toyobo Co., Ltd.)” and “Ecosiale VE100 (Toyobo Co., Ltd.)” obtained by depositing ceramic (silica / alumina) on a polyethylene terephthalate film. And “Ecosia VN100 (manufactured by Toyobo Co., Ltd.)” obtained by depositing ceramic (silica / alumina) on a nylon film. In the present invention, the “tensile strength” of the composite film means a value measured according to JIS-7127.

  The material for forming the light transmission region 9 is not particularly limited, but a material that enables high-precision optical end point detection while polishing and has a light transmittance of 20% or more over the entire wavelength range of 400 to 700 nm is used. It is preferable that the material has a light transmittance of 50% or more. Examples of such materials include polyurethane resins, polyester resins, phenol resins, urea resins, melamine resins, epoxy resins, and acrylic resins, and other thermosetting resins, polyurethane resins, polyester resins, polyamide resins, cellulose resins, Acrylic resin, polycarbonate resin, halogen resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, olefin resin (polyethylene, polypropylene, etc.) and other thermoplastic resins, butadiene rubber, isoprene rubber, etc. Examples thereof include a rubber, a photocurable resin that is cured by light such as ultraviolet rays and an electron beam, and a photosensitive resin. These resins may be used alone or in combination of two or more. The thermosetting resin is preferably one that cures at a relatively low temperature. When using a photocurable resin, it is preferable to use a photopolymerization initiator in combination.

  The photocurable resin is not particularly limited as long as it is a resin that is cured by reaction with light. For example, the resin which has an ethylenically unsaturated hydrocarbon group is mentioned. Specifically, diethylene glycol dimethacrylate, tetraethylene glycol diacrylate, hexapropylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, Polyhydric alcohol-based (meth) acrylates such as dipentaerythritol pentaacrylate, trimethylolpropane trimethacrylate, and oligobutadienediol diacrylate, 2,2-bis (4- (meth) acryloxyethoxyphenyl) propane, bisphenol A or Epoxy (meth) acrylates such as (meth) acrylic acid adducts of epichlorohydrin epoxy resins, phthalic anhydride-neopentylglyco In the reaction of low molecular unsaturated polyester such as a condensate of ru-acrylic acid, (meth) acrylic acid adduct of trimethylolpropane triglycidyl ether, trimethylhexamethylene diisocyanate, dihydric alcohol and (meth) acrylic acid monoester. Urethane (meth) acrylate compound obtained, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene glycol (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, phenoxypolypropylene glycol (meth) acrylate, nonylphenoxypolyethylene glycol (meth) acrylate, And nonylphenoxypolypropylene glycol (meth) acrylate. These may be used alone or in combination of two or more.

  In order to increase the photocurability of the photocurable resin, a photopolymerization initiator, a sensitizer, or the like can be added. These are not particularly limited, and are selected and used according to the light source and wavelength range to be used.

  When ultraviolet rays near i-line (365 nm) are used as a light source, for example, benzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone, 4-methoxy-4′- Aromatic ketones such as dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 2-ethylanthraquinone, and phenanthrenequinone, methylbenzoin, ethylbenzoin and the like Benzoins, benzyl derivatives such as benzyldimethyl ketal, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2- (o-chlorophenyl) -4,5-di (m-methoxyphenyl) imidazole 2-mer, 2- (o-fluorophenyl) -4,5-pheny Imidazole dimer, 2- (o-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (p-methoxyphenyl) -4,5-diphenylimidazole dimer, 2- (2,4- Examples include imidazoles such as dimethoxyphenyl) -4,5-diphenylimidazole dimer, acridine derivatives such as 9-phenylacridine, 1,7-bis (9,9′-acridinyl) heptane, and N-phenylglycine. . These may be used alone or in combination of two or more.

The photosensitive resin is not particularly limited as long as it is a resin that chemically reacts with light. Specifically,
(1) A compound containing an active ethylene group or an aromatic polycyclic compound introduced into the main chain or side chain of a polymer; polyvinyl cinnamate, unsaturated polyester obtained by polycondensation of p-phenylene diacrylic acid with glycol, cinnamylidene Acetic acid esterified with polyvinyl alcohol, cinnamoyl group, cinnamylidene group, chalcone residue, isocoumarin residue, 2,5-dimethoxystilbene residue, styrylpyridinium residue, thymine residue, α-phenylmaleimide, anthracene residue And those having a photosensitive functional group such as 2-pyrone introduced into the main chain or side chain of the polymer.
(2) Diazo group or azido group introduced into the main chain or side chain of the polymer; paraformaldehyde condensate of p-diazodiphenylamine, formaldehyde condensate of benzenediazodium-4- (phenylamino) -phosphate, methoxy Examples include a formaldehyde condensate of a salt addition product of benzenediazodium-4- (phenylamino), polyvinyl-p-azidobenzal resin, and azidoacrylate.
(3) Polymer having phenol ester introduced in main chain or side chain; polymer having unsaturated carbon-carbon double bond such as (meth) acryloyl group introduced, unsaturated polyester, unsaturated polyurethane, unsaturated polymer Examples thereof include saturated polyamide, poly (meth) acrylic acid in which an unsaturated carbon-carbon double bond is introduced as an ester bond in the side chain, epoxy (meth) acrylate, and novolak (meth) acrylate.

  Further, various photosensitive polyimides, photosensitive polyamic acids, photosensitive polyamideimides, and combinations of phenolic resins and azide compounds can be used. Further, it can be used in combination with an epoxy resin or a polyamide introduced with a chemically cross-linked site and a photocationic polymerization initiator. Furthermore, natural rubber, synthetic rubber, or a combination of a cyclized rubber and a bisazide compound can be used.

  The material used for the light transmission region 9 preferably has the same or larger grindability than the material used for the polishing region 8. Grindability refers to the degree to which a workpiece or dresser is shaved during polishing. In such a case, the light transmission region 9 does not protrude from the surface of the polishing region 8, and scratches on the object to be polished and dechucking errors during polishing can be prevented.

  Moreover, it is preferable to use a material similar to the material used for the polishing region 8 or the physical properties of the polishing region 8. In particular, a highly wear-resistant polyurethane resin that can suppress light scattering in the light transmission region 9 due to dressing marks during polishing is desirable.

  The polyurethane resin is composed of an isocyanate component, a polyol component (such as a high molecular weight polyol or a low molecular weight polyol), and a chain extender.

  As the isocyanate component, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, 1,5-naphthalene diisocyanate, Examples include p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and the like. . These may be used alone or in combination of two or more.

  Examples of the high molecular weight polyol include a polyether polyol represented by polytetramethylene ether glycol, a polyester polyol represented by polybutylene adipate, a polycaprolactone polyol, a reaction product of a polyester glycol such as polycaprolactone and an alkylene carbonate, and the like. Exemplified polyester polycarbonate polyol, polyester polycarbonate polyol obtained by reacting ethylene carbonate with polyhydric alcohol and then reacting the obtained reaction mixture with organic dicarboxylic acid, and polycarbonate obtained by transesterification reaction between polyhydroxyl compound and aryl carbonate A polyol etc. are mentioned. These may be used alone or in combination of two or more.

  In addition to the high molecular weight polyols described above as polyols, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1, Low molecular weight polyols such as 4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, and 1,4-bis (2-hydroxyethoxy) benzene may be used in combination.

  Chain extenders include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3 -Low molecular weight polyols such as methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene, or 2,4-toluenediamine, 2,6-toluenediamine, 3,5-diethyl-2,4-toluenediamine, 4,4′-di-sec-butyl-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3,3′-dichloro-4,4′-diaminodiphenylmethane, 2,2 ′, 3,3′-tetrachloro-4,4′- Aminodiphenylmethane, 4,4′-diamino-3,3′-diethyl-5,5′-dimethyldiphenylmethane, 3,3′-diethyl-4,4′-diaminodiphenylmethane, 4,4′-methylene-bis-methyl Anthranilate, 4,4'-methylene-bis-anthranilic acid, 4,4'-diaminodiphenylsulfone, N, N'-di-sec-butyl-p-phenylenediamine, 4,4'-methylene- Bis (3-chloro-2,6-diethylaniline), 4,4′-methylenebis (o-chloroaniline), 3,3′-dichloro-4,4′-diamino-5,5′-diethyldiphenylmethane, 1 , 2-bis (2-aminophenylthio) ethane, trimethylene glycol di-p-aminobenzoate, 3,5-bis (methylthio)- Polyamines exemplified by 2,4-toluenediamine and the like can be mentioned. These may be used alone or in combination of two or more. However, since the polyamines are often colored themselves or resins formed using these are colored in many cases, it is preferable to blend them so as not to impair the physical properties and light transmittance. In addition, when a compound having an aromatic hydrocarbon group is used, the light transmittance on the short wavelength side tends to be lowered. Therefore, it is particularly preferable not to use such a compound. In addition, a compound in which an electron donating group such as a halogen group or a thio group or an electron withdrawing group is bonded to an aromatic ring or the like tends to decrease the light transmittance. Therefore, such a compound may not be used. Particularly preferred. However, you may mix | blend to such an extent that the light transmittance requested | required by the short wavelength side is not impaired.

  The ratio of the isocyanate component, the polyol component, and the chain extender in the polyurethane resin can be appropriately changed depending on the molecular weight of each and the desired physical properties of the light transmission region 9 produced from these. The number of isocyanate groups of the organic isocyanate relative to the total number of functional groups (hydroxyl group + amino group) of the polyol and the chain extender is preferably 0.95 to 1.15, more preferably 0.99 to 1.10. The polyurethane resin can be produced by applying a known urethanization technique such as a melting method or a solution method, but is preferably produced by a melting method in consideration of cost, working environment, and the like.

  As the polymerization procedure of the polyurethane resin, either a prepolymer method or a one-shot method is possible. From the viewpoint of stability and transparency of the polyurethane resin during polishing, an isocyanate-terminated prepolymer from an organic isocyanate and a polyol in advance. Is preferably synthesized, and a prepolymer method in which a chain extender is reacted with this is preferred. Moreover, it is preferable that the NCO weight% of the said prepolymer is about 2 to 8 weight%, More preferably, it is about 3 to 7 weight%. If the NCO wt% is less than 2 wt%, the reaction curing tends to take too much time and the productivity tends to decrease. On the other hand, if the NCO wt% exceeds 8 wt%, the reaction rate becomes too fast. As a result, air entrainment or the like occurs, and physical properties such as transparency and light transmittance of the polyurethane resin tend to deteriorate. When there are bubbles in the light transmission region 9, the attenuation of the reflected light increases due to light scattering, and the polishing end point detection accuracy and the film thickness measurement accuracy tend to decrease. Therefore, in order to remove such bubbles and make the light transmission region 9 non-foamed, it is possible to sufficiently remove the gas contained in the material by reducing the pressure to 10 Torr or less before mixing the material. preferable. Moreover, in the stirring process after mixing, in the case of the stirring blade type mixer normally used, it is preferable to stir at the rotation speed of 100 rpm or less so that bubbles may not mix. In addition, the stirring step is preferably performed under reduced pressure. Furthermore, since the rotation and revolution type mixer is difficult to mix bubbles even at high rotation, it is also preferable to perform stirring and defoaming using the mixer.

  The production method of the light transmission region 9 is not particularly limited, and can be produced by a known method. For example, a polyurethane resin block produced by the above method can be made to have a predetermined thickness using a band saw type or canna type slicer, a method of pouring the resin into a mold having a cavity of a predetermined thickness, a coating technique, A method using a sheet forming technique is used.

  The thickness of the light transmission region 9 is not particularly limited, but when the light transmission region 9 is protruded from the surface of the polishing region 8, the wafer may be damaged by the protruding portion during polishing. On the other hand, when the light transmission region 9 is recessed with respect to the surface of the polishing region 8, a large concave portion is formed on the upper surface of the light transmission region 9, and a large amount of slurry accumulates, which may reduce the optical end point detection accuracy. is there. Therefore, when the light transmission region 9 is provided in the opening 11, the difference in height between the surface of the polishing region 8 and the surface of the light transmission region 9 is preferably 500 μm or less.

  The Asker D hardness of the light transmission region 9 is preferably 30 to 60 degrees. By using the light transmission region 9 having the hardness, generation of scratches on the wafer surface and deformation of the light transmission region 9 can be suppressed. In addition, it is possible to suppress the occurrence of scratches on the surface of the light transmission region 9, thereby making it possible to stably detect the optical end point with high accuracy. The Asker D hardness of the light transmission region 9 is preferably 30 to 50 degrees.

  The surface on the polishing surface side of the light transmission region 9 may be subjected to a roughening treatment in advance. Thereby, the change of the light transmittance of the light transmissive region 9 at the time of use can be suppressed, and when the end point is detected by the program corresponding to the initial light transmittance (light reflectance), the polishing pad is used from the beginning to the end Further, it is possible to prevent the occurrence of an end point detection error accompanying the change in light transmittance.

  As a method for roughening one side of the light transmission region 9, for example, 1) a method for performing sandblasting, embossing, embossing, etching, corona discharge, or laser irradiation on one side of a resin sheet, 2) A method of injection molding or molding using a textured mold, 3) A method of forming a pattern on one side when extruding a resin sheet, 4) A metal roll, rubber roll or emboss having a predetermined surface shape Examples thereof include a method of forming a pattern on one side of a resin sheet using a roll, and 5) a method of buffing using an abrasive such as sandpaper.

  The shape of the roughened surface is not particularly limited, and examples thereof include a continuous pattern, a discontinuous pattern, a linear pattern, a non-linear pattern, a texture pattern, and a pear pattern. In particular, a texture pattern is preferable.

  The arithmetic average roughness (Ra) of the roughened surface is preferably 1 to 2.2 μm, more preferably 1.1 to 1.9 μm. Note that the arithmetic average roughness (Ra) of the surface of the light transmission region 9 on the polishing platen side not subjected to the roughening treatment is usually about 0.3 μm.

  As a material for forming the polishing region 8, for example, polyurethane resin, polyester resin, polyamide resin, acrylic resin, polycarbonate resin, halogen resin (polyvinyl chloride, polytetrafluoroethylene, polyvinylidene fluoride, etc.), polystyrene, olefin resin (Polyethylene, polypropylene, etc.), epoxy resin, photosensitive resin, and the like. These may be used alone or in combination of two or more. The forming material of the polishing region 8 may be the same as or different from that of the light transmitting region 9, but it is preferable to use the same type of material as that used for the light transmitting region 9.

  Polyurethane resin is a particularly preferable material for forming the polishing region 8 because it is excellent in abrasion resistance and a polymer having desired physical properties can be easily obtained by variously changing the raw material composition.

  The isocyanate component to be used is not particularly limited, and examples thereof include the isocyanate component.

  The high molecular weight polyol to be used is not particularly limited, and examples thereof include the high molecular weight polyol. In addition, the number average molecular weight of these high molecular weight polyols is not particularly limited, but is preferably 500 to 2000 from the viewpoint of the elastic characteristics of the obtained polyurethane. If the number average molecular weight is less than 500, a polyurethane using the number average molecular weight does not have sufficient elastic properties and becomes a brittle polymer. For this reason, the polishing region 8 manufactured from this polyurethane becomes too hard and causes scratches on the wafer surface. Moreover, since it becomes easy to wear, it is not preferable from the viewpoint of the pad life. On the other hand, if the number average molecular weight exceeds 2000, the polyurethane using this becomes too soft, and the polishing region 8 produced from this polyurethane tends to be inferior in flattening characteristics.

  Moreover, as a polyol, the said low molecular weight polyol can also be used together besides a high molecular weight polyol.

  As chain extenders, 4,4′-methylenebis (o-chloroaniline) (MOCA), 2,6-dichloro-p-phenylenediamine, 4,4′-methylenebis (2,3-dichloroaniline), 3, 5-bis (methylthio) -2,4-toluenediamine, 3,5-bis (methylthio) -2,6-toluenediamine, 3,5-diethyltoluene-2,4-diamine, 3,5-diethyltoluene- 2,6-diamine, trimethylene glycol-di-p-aminobenzoate, polytetramethylene oxide-di-p-aminobenzoate, 1,2-bis (2-aminophenylthio) ethane, 4,4′-diamino- 3,3′-diethyl-5,5′-dimethyldiphenylmethane, N, N′-di-sec-butyl-4,4′-diaminodiphenylmethane, 4, '-Diamino-3,3'-diethyldiphenylmethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3'-diisopropyl-5 5'-dimethyldiphenylmethane, 4,4'-diamino-3,3 ', 5,5'-tetraethyldiphenylmethane, 4,4'-diamino-3,3', 5,5'-tetraisopropyldiphenylmethane, m-xyl Examples include polyamines exemplified by range amine, N, N′-di-sec-butyl-p-phenylenediamine, m-phenylenediamine, and p-xylylenediamine, or the low molecular weight polyol component described above. it can. These may be used alone or in combination of two or more.

  The ratio of the isocyanate component, the polyol component, and the chain extender in the polyurethane resin can be variously changed depending on the molecular weight of each and the desired physical properties of the polishing region 8 produced from these. In order to obtain a polishing region 8 having excellent polishing characteristics, the number of isocyanate groups of the isocyanate component relative to the total number of functional groups (hydroxyl group + amino group) of the polyol component and the chain extender is preferably 0.95 to 1.15. More preferably, it is 0.99 to 1.10.

  The polyurethane resin can be produced by the same method as described above. In addition, stabilizers such as antioxidants, surfactants, lubricants, pigments, solid beads, fillers such as water-soluble particles and emulsion particles, antistatic agents, abrasive grains, and other materials as necessary. Additives may be added.

  The polishing region 8 is preferably a fine foam. By using a fine foam, the slurry can be held in the fine pores on the surface, and the polishing rate can be increased.

  The method for finely foaming the polyurethane resin is not particularly limited, and examples thereof include a method of adding hollow beads, a method of foaming by a mechanical foaming method, a chemical foaming method, and the like. In addition, although each method may be used together, the mechanical foaming method using the silicon type surfactant which is a copolymer of polyalkylsiloxane and polyether is especially preferable. Examples of the silicon-based surfactant include SH-192, L-5340 (manufactured by Toray Dow Corning Silicon), and the like.

An example of a method for producing a micro-bubble type polyurethane foam will be described below. The manufacturing method of this polyurethane foam has the following processes.
1) Foaming process for producing a cell dispersion of isocyanate-terminated prepolymer A silicon-based surfactant is added to the isocyanate-terminated prepolymer (first component), and the mixture is stirred in the presence of a non-reactive gas to remove the non-reactive gas. Disperse as fine bubbles to obtain a cell dispersion. When the prepolymer is solid at normal temperature, it is preheated to an appropriate temperature and melted before use.
2) Curing Agent (Chain Extender) Mixing Step A chain extender (second component) is added to the above cell dispersion, mixed and stirred to obtain a foaming reaction solution.
3) Casting process The above foaming reaction liquid is poured into a mold.
4) Curing process The foaming reaction liquid poured into the mold is heated and reacted and cured.

  As the non-reactive gas used to form the fine bubbles, non-flammable gases are preferable, and specific examples include nitrogen, oxygen, carbon dioxide, rare gases such as helium and argon, and mixed gases thereof. The use of air that has been dried to remove moisture is most preferable in terms of cost.

  As a stirring device for making non-reactive gas into fine bubbles and dispersing it in an isocyanate-terminated prepolymer containing a silicon-based surfactant, a known stirring device can be used without particular limitation. Specifically, a homogenizer, a dissolver, A two-axis planetary mixer (planetary mixer) is exemplified. The shape of the stirring blade of the stirring device is not particularly limited, but it is preferable to use a whipper-type stirring blade because fine bubbles can be obtained.

  In addition, it is also a preferable aspect to use a different stirring apparatus for the stirring which produces a bubble dispersion liquid in the stirring process, and the stirring which adds and mixes the chain extender in a mixing process. In particular, the stirring in the mixing step may not be stirring that forms bubbles, and it is preferable to use a stirring device that does not involve large bubbles. As such an agitator, a planetary mixer is suitable. There is no problem even if the same stirring device is used as the stirring device for the stirring step and the mixing step, and it is also preferable to adjust the stirring conditions such as adjusting the rotation speed of the stirring blade as necessary. .

  In the production method of polyurethane foam, heating and post-curing the foam that has reacted until the foaming reaction liquid is poured into the mold and no longer flows is effective in improving the physical properties of the foam and is extremely suitable. It is. The foam reaction solution may be poured into the mold and immediately put into a heating oven for post cure, and heat is not immediately transferred to the reaction components under such conditions, so the bubble size does not increase. . The curing reaction is preferably performed at normal pressure because the bubble shape is stable.

  In the production of the polyurethane resin, a catalyst that promotes a known polyurethane reaction such as a tertiary amine type or an organic tin type may be used. The type and addition amount of the catalyst are selected in consideration of the flow time for pouring into a mold having a predetermined shape after the mixing step.

  The polyurethane foam may be produced by a batch method in which each component is metered into a container and stirred, and each component and a non-reactive gas are continuously supplied to the stirring device and stirred to produce bubbles. It may be a continuous production method in which a dispersion is sent out to produce a molded product.

  The average cell diameter of the polyurethane foam is preferably 30 to 80 μm, more preferably 30 to 60 μm. When deviating from this range, the polishing rate tends to decrease, or the planarity of the polished material (wafer) after polishing tends to decrease.

  The specific gravity of the polyurethane foam is preferably 0.5 to 1.3. When the specific gravity is less than 0.5, the surface strength of the polishing region 8 decreases, and the planarity of the material to be polished tends to decrease. On the other hand, when the ratio is larger than 1.3, the number of bubbles on the surface of the polishing region 8 is reduced and the planarity is good, but the polishing rate tends to decrease.

  The hardness of the polyurethane foam is preferably 45 to 70 degrees as measured by an Asker D hardness meter. When the Asker D hardness is less than 45 degrees, the planarity of the material to be polished is lowered. When the Asker D hardness is more than 70 degrees, the planarity is good but the uniformity of the material to be polished is lowered. There is a tendency.

  The polishing region 8 is produced by cutting the polyurethane foam produced as described above into a predetermined size.

  In the polishing region 8, it is preferable that a concavo-convex structure (grooves or holes) for holding and renewing the slurry is provided on the polishing side surface in contact with the wafer. When the polishing region 8 is formed of a fine foam, it has a large number of openings on the polishing surface and has a function of holding the slurry. However, it further efficiently retains the slurry and renews the slurry. For this reason, it is preferable that the polishing side surface has a concavo-convex structure in order to prevent dechucking errors due to wafer adsorption, wafer breakage, and reduction in polishing efficiency. The concavo-convex structure is not particularly limited as long as it is a surface shape that holds and renews slurry. For example, XY lattice grooves, concentric grooves, through holes, non-through holes, polygonal columns, cylinders, spiral grooves , Eccentric circular grooves, radial grooves, and combinations of these grooves. Further, the groove pitch, groove width, groove depth and the like are not particularly limited and are appropriately selected and formed. Furthermore, these uneven structures are generally regular, but in order to make the slurry retention and renewability desirable, the groove pitch, groove width, groove depth, etc. should be changed for each range. Is also possible.

  Although the thickness of the grinding | polishing area | region 8 is not specifically limited, Usually, it is about 0.8-4 mm, and it is preferable that it is 1.5-2.5 mm. As the method for producing the polishing region 8 having the above thickness, a method in which the fine foam block is made to have a predetermined thickness using a band saw type or canna type slicer, or a resin is poured into a mold having a cavity having a predetermined thickness. Examples of the curing method include a method using a coating technique and a sheet molding technique.

  The cushion layer 13 supplements the characteristics of the polishing region 8. The cushion layer 13 is necessary for achieving both planarity and uniformity in a trade-off relationship in CMP. Planarity refers to the flatness of a pattern portion when a polished object with minute irregularities generated during pattern formation is polished, and uniformity refers to the uniformity of the entire object to be polished. The planarity is improved by the characteristics of the polishing region 8, and the uniformity is improved by the characteristics of the cushion layer 13. In the polishing pad of the present invention, the cushion layer 13 is preferably softer than the polishing region 8.

  The material for forming the cushion layer 13 is not particularly limited. For example, a fiber nonwoven fabric such as a polyester nonwoven fabric, a nylon nonwoven fabric, and an acrylic nonwoven fabric, a resin-impregnated nonwoven fabric such as a polyester nonwoven fabric impregnated with polyurethane, a polymer resin such as polyurethane foam, polyethylene foam, etc. Examples thereof include rubber resins such as foam, butadiene rubber and isoprene rubber, and photosensitive resins.

Although the manufacturing method in particular of the polishing pad 1 of this invention is not restrict | limited, For example, the following method is mentioned.
1) A double-sided tape is stuck on both sides of the composite film constituting the intermediate layer 12, and a cushion layer 13 is stuck on one side.
2) The polishing region 8 in which the first opening 11 is formed is bonded to the cushion layer 13 via the intermediate layer 12.
3) Part of the intermediate layer 12 and the cushion layer 13 in the first opening 11 is removed from the polishing region 8 side, and the second opening 14 is formed in the intermediate layer 12 and the cushion layer 13.
4) The light transmission region 9 is disposed on the second opening 14 and in the first opening 11 so as to contact the intermediate layer 12.

  As a means for adhering the polishing region 8 and the cushion layer 13 through the intermediate layer 12, as described above, for example, the polishing region 8 and the cushion layer 13 are sandwiched between the intermediate layer 12 having a double-sided tape attached to both sides. And a pressing method. The double-sided tape has a general configuration in which adhesive layers are provided on both sides of a substrate such as a nonwoven fabric or a film. Examples of the composition of the adhesive layer include rubber adhesives and acrylic adhesives. When the polishing end point is detected by an optical detection means and an acidic slurry is used, a rubber adhesive is preferable from the viewpoint of chemical resistance. In addition, since the composition may differ between the grinding | polishing area | region 8 and the cushion layer 13, it is also possible to make the composition of each contact bonding layer of a double-sided tape different, and to optimize the adhesive force of each layer.

  The means for forming openings in the polishing region 8, the intermediate layer 12 and the cushion layer 13 is not particularly limited. For example, a method of opening by punching with a blade type (Thomson blade or the like), pressing with a cutting tool, or Examples thereof include a method of opening by grinding, a method of using a laser by a carbonic acid laser, and the like. The size and shape of the opening are not particularly limited.

  The semiconductor device is manufactured through a step of polishing the surface of the semiconductor wafer using the polishing pad. A semiconductor wafer is generally a laminate of a wiring metal and an oxide film on a silicon wafer. The method and apparatus for polishing the semiconductor wafer are not particularly limited. For example, as shown in FIG. 1, a polishing surface plate (platen) 2 that supports the polishing pad 1 and a support table 5 (polishing head) that supports the semiconductor wafer 4. And a polishing apparatus equipped with a backing material for uniformly pressing the wafer and a supply mechanism of the abrasive 3. The polishing pad 1 is attached to the polishing surface plate 2 by attaching it with a double-sided tape, for example. The polishing surface plate 2 and the support base 5 are disposed so that the polishing pad 1 and the semiconductor wafer 4 supported on each of the polishing surface plate 2 and the support table 5 face each other, and are provided with rotating shafts 6 and 7 respectively. Further, a pressurizing mechanism for pressing the semiconductor wafer 4 against the polishing pad 1 is provided on the support base 5 side. In polishing, the semiconductor wafer 4 is pressed against the polishing pad 1 while rotating the polishing surface plate 2 and the support base 5, and polishing is performed while supplying acidic slurry. The flow rate of the acidic slurry, the polishing load, the polishing platen rotation speed, and the wafer rotation speed are not particularly limited, and are adjusted as appropriate.

  As a result, the protruding portion of the surface of the semiconductor wafer 4 is removed and polished flat. Thereafter, a semiconductor device is manufactured by dicing, bonding, packaging, or the like. The semiconductor device is used for an arithmetic processing device, a memory, and the like.

[Other Embodiments]
Hereinafter, other embodiments of the present invention will be described.

  In the above-described embodiment, as shown in FIG. 3, an annular water-impermeable elastic member 16 that covers the contact portion is disposed at the contact portion between the back surface of the light transmission region 9 and the cross section of the second opening 14. May be. According to such a configuration, the contact portion between the back surface of the light transmission region 9 and the cross section of the second opening portion 14 can be completely sealed, so that it is possible to more reliably prevent slurry leakage. The material for forming the water-impermeable elastic member 16 is not particularly limited as long as the material has water resistance and elasticity. For example, a composition containing a water-impermeable resin such as rubber, thermoplastic elastomer, or reaction curable resin. (Adhesive or adhesive).

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated, this invention is not limited to these Examples.

[Measurement and evaluation methods]
(Water vapor permeability)
Based on JIS-7129, the water vapor transmission rate (g / m < ² > * day) was measured. The measurement results are shown in Table 1.

(Tensile strength)
The tensile strength (MPa) was measured according to JIS-7127. The measurement results are shown in Table 1.

(Presence or absence of water droplets or cloudiness on the back of the light transmission area)
SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) was used as a polishing apparatus, and after polishing a predetermined number of wafers using the prepared polishing pad, the presence or absence of water droplets or cloudiness on the back surface of the light transmission region was visually observed. Table 1 shows the observation results and the number of polished wafers when water droplets and / or fogging actually occurred.

(Evaluation of polishing characteristics)
Using SPP600S (manufactured by Okamoto Machine Tool Co., Ltd.) as a polishing apparatus, polishing characteristics were evaluated using the prepared polishing pad. The settings at the time of polishing are as follows.
Polishing rotation speed: 90/90 rpm (platen / head), polishing pressure: 4 psi, polishing time: 1 min
Dresser: M-100 type manufactured by Asahi Diamond, dress pressure: 250 g / cm ² , rotational speed: 30/15 rpm (platen / head), ex-situ dress time: 20 sec, initial dress time: 15 min
・ Slurry: Cabot W2000 diluted twice with ultra pure water and added with 2% by weight of H ₂ O ₂
The polishing rate was calculated from the film thickness at this time after polishing a 1-μm tungsten film formed on an 8-inch silicon wafer for 1 min. The polishing rate was calculated using the average value of the film thickness measured values at 25 specific positions on the wafer as shown in FIG. Table 1 shows the polishing rates for the 10th, 150th, 300th and 500th wafers. For measuring the film thickness of the tungsten film, a non-contact sheet resistance measuring device (manufactured by Napson) was used. As polishing conditions, a polishing pad was bonded to the platen, 15 min initial dressing, 1 min polishing / 20 sec ex-situ dressing was repeated, and pseudo polishing with a silicon wafer was performed up to 500 sheets.

As shown in FIG. 4, in-plane uniformity is evaluated by obtaining a polishing rate maximum value and a polishing rate minimum value from measured film thickness values before and after polishing at 25 specific positions on a tungsten wafer, and substituting these values into the following equation. It was calculated by doing. Table 1 shows the in-plane uniformity of the 10th, 150th, 300th and 500th wafers. Note that the smaller the in-plane uniformity value, the higher the uniformity of the wafer surface.
In-plane uniformity (%) = {(maximum polishing rate−minimum polishing rate) / (maximum polishing rate + minimum polishing rate)} × 100

Example 1
[Production of light transmission region]
A thermoplastic polyurethane A1098A (manufactured by Toyobo Co., Ltd.) was used to produce a light transmission region (shape: vertical 19.0 mm × horizontal 57.0 mm × thickness 1.25 mm, D hardness 48 degrees) by injection molding.

[Production of polishing area]
In a reaction vessel, 100 parts by weight of a polyether-based prepolymer (manufactured by Uniroyal Corporation, adiprene L-325, NCO concentration: 2.22 meq / g), and a silicon-based surfactant (manufactured by Toray Dow Corning Silicone, SH- 192) 3 parts by weight were mixed and the temperature was adjusted to 80 ° C. Using a stirring blade, the mixture was vigorously stirred for about 4 minutes so that bubbles were taken into the reaction system at 900 rpm. 26 parts by weight of 4,4′-methylenebis (o-chloroaniline) (Ihara Chemical amine, manufactured by Ihara Chemical Co.) previously melted at 120 ° C. was added thereto. Thereafter, stirring was continued for about 1 minute, and the reaction solution was poured into a pan-shaped open mold. When the fluidity of this reaction solution disappeared, it was put in an oven and post-cured at 110 ° C. for 6 hours to obtain a polyurethane foam block. This polyurethane foam block was sliced using a band saw type slicer (manufactured by Fecken) to obtain a polyurethane foam sheet (density 0.86, D hardness 52 degrees). Next, this sheet was subjected to surface buffing to a predetermined thickness using a buffing machine (Amitech Co., Ltd.) to obtain a sheet with adjusted thickness accuracy (sheet thickness: 1.27 mm). The buffed sheet was punched to a predetermined diameter (60 cm), and then a first opening of 19.5 mm in length and 57.5 mm in width was formed at a position about 30 cm from the center of the punched sheet. Further, a concentric groove processing (groove width 0.25 mm, depth 0.45 mm, pitch 1.5 mm) was performed on the surface using a groove processing machine (manufactured by Toho Steel Machine Co., Ltd.) to prepare a polished region.

[Production of polishing pad]
A rubber-based double-sided tape (manufactured by Sekisui Chemical Co., Ltd.) was attached to one surface of a composite film “Ecosia VE500 (manufactured by Toyobo Co., Ltd.)” obtained by depositing ceramic (silica / alumina) on a polyethylene terephthalate (PET) film. A laminate layer made of urethane foam (density 0.55, C hardness 50, thickness 1.25 mm) and having a double-sided tape previously bonded to the platen side surface was bonded using a laminator. Next, a rubber-based double-sided tape was attached to the other surface of the composite film, and was bonded to the polishing area using a laminator. Further, a part of the composite film (intermediate layer) and the cushion layer in the first opening is removed from the polishing region side, and a second opening (vertical 11.0 mm × width 50.0 mm) is formed in the intermediate layer and the cushion layer. Formed. Furthermore, the polishing pad shown in FIG. 2 was created by disposing a light transmission region on the second opening and in the first opening so as to contact the intermediate layer.

(Example 2-3)
A polishing pad was produced in the same manner as in Example 1 except that the composite film “Ecosia VE100 (manufactured by Toyobo Co., Ltd.)” obtained by depositing ceramic (silica / alumina) on a PET film as an intermediate layer was used. (Example 2). Further, in Example 1, a polishing pad was used in the same manner as in Example 1 except that a composite film “Ecosia VN100 (manufactured by Toyobo Co., Ltd.)” obtained by depositing ceramic (silica / alumina) on a nylon film as an intermediate layer was used. (Example 3).

(Comparative Example 1-3)
In Example 1, an untreated (non-deposited ceramic) PET film (Comparative Example 1), an untreated (non-deposited ceramic) nylon film (Comparative Example 2), or an untreated (deposited ceramic) No) A polishing pad was produced in the same manner as in Example 1 except that a hard vinyl chloride (PVC) film (Comparative Example 3) was used.

  From Table 1, in the polishing pad of Example 1-3, water droplets and fogging did not occur on the back surface of the light transmission region even after 700 wafers were polished. Further, in the polishing pad of Example 1-3, when 600 wafers were polished, the concentric grooves on the surface of the polishing layer disappeared due to wear, but the in-plane uniformity up to the 500th wafer disappeared was 10%. And showed good results. Also, the polishing rate showed stable results. On the other hand, before the polishing pad of Comparative Example 1-3 polished about 300 wafers, water droplets and fogging occurred on the back surface of the light transmission region. Further, the in-plane uniformity deteriorated with time and the polishing rate was not stable.

Schematic configuration diagram showing an example of a polishing apparatus used in CMP polishing An example of a schematic sectional view of a polishing pad according to the present invention Another example of schematic sectional view of polishing pad according to the present invention Schematic showing 25 film thickness measurement positions on wafer

Explanation of symbols

1: Polishing pad 2: Polishing surface plate (platen)
3: Abrasive (slurry)
4: Material to be polished (semiconductor wafer)
5: Support base (polishing head)
6, 7: Rotating shaft 8: Polishing region 9: Light transmission region 10: Polishing layer 11: First opening 12: Intermediate layer 13: Cushion layer 14: Second opening

Claims (4)

A polishing pad in which a polishing layer is laminated on a cushion layer via an intermediate layer,
The polishing layer includes a polishing region in which a first opening is formed, and a light transmission region disposed in the first opening and in contact with the intermediate layer,
The intermediate layer and the cushion layer include a second opening formed to be smaller than the light transmission region and overlap the light transmission region,
The polishing pad according to claim 1, wherein the intermediate layer is a composite film obtained by depositing ceramic on a resin film.   The polishing pad according to claim 1, wherein the composite film has a tensile strength of 50 to 500 MPa and a thickness of 3 to 125 μm. A polishing pad in which a polishing layer is laminated on a cushion layer via an intermediate layer,
The polishing pad according to claim 1, wherein the intermediate layer is a composite film obtained by depositing ceramic on a resin film.   A method for manufacturing a semiconductor device, comprising a step of polishing a surface of a semiconductor wafer using the polishing pad according to claim 1.

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